Respiratory health effects from exposure to carbon black: results of the phase 2 and 3 cross sectional studies in the European carbon black manufacturing industry

OBJECTIVES: To assess respiratory morbidity over several cross sectional phases in the European carbon black manufacturing industry. METHODS: Participants completed an amended (and translated) MRC respiratory morbidity questionnaire with additional questions on previous exposures, job history, etc, and spirometry traces in each phase. Concurrent with the health outcome measures, personal exposure to inhalable dust was measured. RESULTS: Percentage participation rose from 90% in phase 2 (19 factories) to 95% in phase 3 (16 factories). Exposure dropped slightly between the 2 and 3 phases; as did the prevalence of reporting symptoms. Percentage of predicted lung function volumes exceeded 100% for forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC), whereas forced mid-expiratory flow (FEF(25%-75%)) and FEV(1)/FVC ratio were below 100% in both phases. The multiple linear and logistic regressions showed that carbon black had a significant effect on lung function and on most respiratory symptoms, respectively. CONCLUSION: Both current and cumulative exposure to carbon black have a deleterious effect on respiratory morbidity. Due to the drop in exposure between phases 2 and 3, recent exposures seem to have less of an impact on the respiratory morbidity in the workers in phase 3 than those in phase 2.